1. Field of the Invention
The present invention relates to a connecting device for connecting a cloth pulling arrangement to a sewing machine.
2. Description of the Related Art
A cloth pulling arrangement known in the prior art is designed specifically for a general purpose sewing machine already used in a ready-made clothes factory. After installation of the cloth pulling arrangement on a back of a sewing machine, a cloth pulling roller is driven by a main shaft of the sewing machine, and a belt, a governor, and a driving shaft of the cloth pulling arrangement are driven, in turn, to cope with the up-and-down movement of a needle of the sewing machine in order to pull the cloth in the sewing machine taut to resist formation of wrinkles in cloth during operation of the sewing machine and to maintain the sewn portion flat, neat and beautiful.
When the cloth pulling arrangement is added to the sewing machine, it must conform to the shape and structure of the sewing machine. It is known to utilize two connecting frames to install the pulling arrangement on a back of a post of the sewing machine.
One connecting frame is used specifically to fix the governor of the cloth pulling arrangement on the back of the post of the sewing machine. In addition, an end connecting frame is used to replace the original end plate and to fix the components of the cloth pulling arrangement, such as a pulling roller, solenoid actuator, etc. on the back of the end of a hanging arm of the sewing machine.
In order to satisfy the general custom of the operator during operation, in the majority of the time of operation, the cloth is sewn in a forward direction, and the operating direction of the cloth pulling arrangement is also designed to keep pace with the forward sewing; however, back sewing in the reverse direction is also required sometimes. During this back sewing period, the cloth pulling roller of the cloth pulling arrangement must be disengaged from the cloth. Under such circumstances, the solenoid actuator of the cloth pulling arrangement must act to lift up the pulling roller. In order to make the action of the solenoid actuator and the back sewing of the sewing machine completely synchronous, a limit switch is added below the back sewing lever of the sewing machine. When the operator wants to begin back sewing, the back sewing lever only is depressed, and then the sewing machine would begin the back sewing operation. The back sewing lever triggers the limit switch which causes the solenoid actuator to lift up the cloth pulling roller.
There are many brands of sewing machines, the trade marks of those most frequently used being Brother, Juki, Toyota, Singer ... too many to be enumerated, and each manufacturer produces various kinds of sewing machines. Besides, even sewing machines of the same type are divided into (1) automatic thread cutting (i.e. to cut off the thread automatically after completion of sewing), and (2) without automatic thread cutting. Thus, there are more than one hundred sewing machine types. More importantly, new machine types are constantly being introduced in the market, and the quantity of sewing machines of different types is increasing continuously.
In order that the cloth pulling arrangement might be installed on different shapes of sewing machines, the manufacturer of the known cloth pulling arrangement produces more than one hundred shapes of two-piece "connecting frames". In the meantime, owing to new types of sewing machines being constantly introduced into the market, the manufacturer of the known cloth pulling arrangement must increase the number of connecting frames to fit such new machine types in order to meet the requirements of ready-made clothes manufacturers. Under such circumstances, both the manufacturers of ready-made clothes and cloth pulling arrangements have been annoyed by the following problems:
1. The enormous warehousing of connecting frames annoyed the manufacturers of cloth pulling arrangements in management, manufacture and in installing the connecting frames on the scene of a sewing machine,
2. The complicated classification and specification of the connecting frames caused misunderstanding during communication between the manufacturers of ready-made clothes and cloth pulling arrangements which resulted in annoyance,
3. The process of installation of the connecting frames was troublesome; it had to be performed by an expert; ordinary ready-made clothes factories were unable to install it by themselves. It was really inconvenient to request the manufacturer of cloth pulling arrangement to dispatch a technician to install the connecting frames, and
4. Many holes had to be drilled into the sewing machine in order to fix the connecting frames. It would not only ruin the external look of the sewing machine, but also selecting appropriate positions on the case of the sewing machine of a special shape was also difficult.